Air conditioning system and apparatus



Oct. 29, 1963 A. F. CLIFFORD AIR CONDITIONING SYSTEM AND APPARATUS FiledJuly 20. 1960 36"" n In INVENTOR. ARTHUR E C FFORD AT ORNEY UnitcdStates Patent 3,103,451 A CQNDITEONHJG SYSTEM AND APPARATUS Arthur F.Clifford, 151 E. Pasadena, Phoenix, Ariz.,

assignor of thirty-seven and one-haif percent to H. Leslie Hill, Dallas,Tex., and twenty-five percent to Jose Acosta, Phoenix, Ariz.

Filed July 20, 1%9, Ser. No. 44,047 5 Claims. (Cl. 62184-) My inventionrelates in general to air conditioning systems and more in particular tothe selective cooling of the condenser portion of the system in responseto pre-selected loading of the compressor.

Conventional refrigeration systems employing modern relatively low vaporpressure and high specific heat types of refrigerants operate on theprincipal of compressing the refrigerant to a liquid, passing thecompressed refrigerant to a condenser coil, cooling the condenser coilto stabilize the refrigerant in liquid condition, delivering the liquidrefrigerant to an expansion coil where it is evaporated and adsorbs heatfrom the coil and its surroundings, and returning the vaporousrefrigerant to the input side of the compressor to complete the cycle.Air is passed over the expansion coil, commonly called the cooling coilin air conditioning parlance, and the air cooled by contact with thecooling coil is delivered continuously and by recirculation to the spaceto be cooled. Conventionally the condenser is cooled either by air or bymeans of liquid in a heat exchanger.

While the arrangement of equipment in a system may vary extensively, ithas become a common practice in relatively small air conditioningsystems suitable for homes to mount the compressor and condenser in aseparate unit outside the home and to utilize ambient air for coolingthe condenser, the air being passed over the condenser coil by a blowercommonly mounted in the outside unit. It is known that there is a lossof efiiciency and some increase in operating costs when ambient air isused for cooling the condenser and there have been several approaches tothe solution of this problem. A common approach of several manufacturersis to attempt to balance up the different factors and equilibriainvolved to increase efficiency in the environment in which the systemis operated, including for example operating the system at a somewhathigher back pressure on the input side of the compressor and increasingthe volume of air passed over the condenser coil. The use ofrefrigerated air to cool the condenser coil has also been suggested, butsince the employment of refnigerated air for this purpose represents aloss to the air cooling portion of the system, over-all efficiency isnot improved. Most recently water has been sprayed on or near thecondenser coils for the purpose of supplementing the cooling action of anormal air cooled condenser system, and while eiliciency of the systemand reduced operating costs have resulted from this supplementary waterspray procedure, water scaling of surfaces also occurs and extensivecleaning and/ or replacement of parts becomes necessary in anywhere fromone to three years.

The principal object of my present invention is the production of animproved air conditioning system.

Another object is to improve the efficiency of a normal air cooledcompressor and condenser system.

Still another object is to supplement the cooling action of ambient airby water evaporation when ambient conditions result in the placing of apredetermined load on the refrigerant compressor.

Still another object is to utilize water to supplement the coolingaction of ambient air in such a way as to avoid the objectionablefeatures of supplementary water cooling as used in the prior art.

In accordance with the main features of my invention,

I provide an absorbent pad through which ambient cooling air passes onits way to the condenser and delivers a relatively small amount of waterto such pad in response to a predetermined rise in pressure on theoutlet side of the compressor and between the compressor and thecondenser. Water is delivered to the pad from an ordinary Water supplyline only when the load placed on the compressor reaches a predeterminedlevel. The system of the present invention can be built into the usualcompressor, condensor, blower unit of household refrigerating systems,or it may be applied to an existing system already in operation. Ineither case efficiency of the system as evidenced by reduced power costsis greatly increased with the deleterious deposit of scale such asoccurs in systems of the prior art heretofore employed.

In the drawings,

FIG. 1 is a composite view showing the system of my present invention,some of the parts being shown structurally and some schematically;

FIG. 2 isa sectional view of one type of pressure responsive watercontrol valve which may be used in the system.

Referring now to the drawings, the numeral 10 identifies a usual type ofhousing substantially imperforate so that air drawn through the intake11 of a blower 12 and delivered through a discharge opening 13 passesthrough the intake side 14- past a compressor 16 and over a condensercoil 17. Normally a blower of the type shown has an intake 11 at bothsides thereof. It should be understood that the installation shown iscompletely illustrative as any type of blower and air movement systemmay be used in which the air is either drawn across the condenser asindicated in the drawing or blown across the condenser as occurs in sometypes of installations.

In the form shown, the compressor 16 draws vaporous refrigerant througha line 18 and delivers it to a header 19 of the condenser through a highpressure line 21. The condenser has a series of copper tubes 22.provided with fins 23 to provide an increased heat exchange surface, allof which structure is conventional and may be of any usual construction.The condensed refrigerant is delivered through a tube 24 to a coolingcoil 26 which also has a series of tubes 27 and fins 28. A blower 29draws room air from the usual return register (not shown) and deliversit over the coils and fins of the cooling coil through a duct system 31back to the room space being refrigerated. The expanded vaporousrefrigerant passes from the cooling coil 26 to the line 18 to completethe refrigerant cycle.

At the air intake side of the housing or casing 10 I provide anevaporator 32 having a shallow trough 33 at its top and a plurality ofabsorbent pads 34 separated by transverse strips 36 which may be porousasbestos or any suitable strip running the full width of the evaporator.In the drawings I show small openings 37 in the water retaining andspreader strips 34 to indicate slow gravity movement of water throughsuch strips. The absorbent pads 36 may be any suitable materialproviding a relatively large evaporative surface which is wettedrelatively quickly by wvater and may comprise any of the usual padmaterials employed in ordinary evaporative coolers such as excelsiortreated to increase its water absorption and decrease fungicidal action.

Water is delivered to the trough 33 through a pipe 38 leading to apressure responsive valve 39, the water supply being through arelatively small pipe 41 leading to an ordinary water line 42 furnishingwater to the home. The pressure responsive expansion valve 39 isconnected by a tube 43 to the line 21 running iro-m the pressure side ofthe compressor to the condenser 17. The pressure responsive valve 39 maybe of any suitable common type. In FIG. 2 one such type which I haveemployed success- C) fully has a seat 46 between an intake chamber 47and an outlet chamber 48 which connect to lines 4 1 and 38 respectively,normally closed by a valve 49 on a stem 51 biased downwardly by a spring52. T'he stem 51 extends downwardly into a diaphragm chamber '53 sealedby a diaphragm 54 so constructed and arranged that pressure on theoutside of the diaphragm through line 43 will raise the diaphragmassembly and lift the valve stem and valve. The compression of spring 52may be controlled by exterior adjusting nut 56 so that the valve may beadjusted to open in response to a predetermined pressure within thelimits of its design. Since, as will be explained, the pressureresponsive valve should open when the compressor is operating at apredetermined pressure, for example about 200 pounds per square inch,the valve should be selected to be effective between limits includingthe selected range to which the valve is to be responsive.

In operating the system of my present invention, there are advantagesboth from the standpoint of operating efficiency as evidenced byreduction in power consumption of about when the water evaponative padsystem including the pressure responsive valve 39 is added to anexisting system, and from the standpoint of revised engineering of theentire system in a new installation giving rise to still increasedsavings. Since air conditioning systems vary somewhat in their design aswell as operating costs in various parts of the country, the advantagesand functions of the present invention will be described by reference toclimatic conditions usually encountered in southern Arizona.

In the desert .and semi-desert areas of the southwest, ambienttemperatures may vary during a refrigerating season between and orconsidering both the diurnal and nocturnal variations. The rule of thumbfor air cooled relatively small (one to five tons for example) airconditioning systems is to employ two square feet of condenser percompressor horsepower based on the use of a condenser coil which isthree tubes deep and is provided with ten fins per square inch.Conventionally, also, a cooling coil will be provided having one squarefoot of area for each two square feet of condenser area, with thecooling coil also being three tubes deep and having ten fins per linealinch. This relationship is illustrative and of course may vary somewhatfrom installation to installat-ion. eighty pounds back pressure asmeasured at the intake side of the compressor and up to 425 pounds persquare inch at the discharge side of the compressor between thecompressor and condenser coil. When the evaporator pad 32 is employed,it is preferably about one to one and one-half inches in thickness sothat air will readily pass through it without overloading the blower1'1, and it pref erably has .an area approximately equal to the area ofthe condenser. These dimensions for the evaporative pad 32 may of coursevary somewhat with the available space, particularly in an alreadyinstalled system. If it is neces sary to restrict the over-all area ofthe pad 32 it can be made somewhat thicker so that it will still supplythe same required evaporative surface. If now into the system asdescribed the pressure responsive valve 39 is introduced, installed asshown in the drawing and adjust to open at 200 pounds pressure, the backpressure on the system will normally drop to about sixty to sixty-fivepounds per square inch, and the pressure at the discharge side of thecompressor will normally drop to the 180 to 260 pound range dependingupon the ambient temperature.

The water delivered to the trough 33 should be just suflicient tomoisten the entire pad surface, allowing only a very small amount ofexcess, or possibly none at all during the period of maximum ambienttemperature and lowest relative humidity. Any excess non-evaporatedwater drops to a drain board 58 where it is allowed to run ofi, andsince it is always small in amount no problem of drainage occurs. Thepipe 41 is normally dimensioned, taking into consideration the normalwater pressure, so

Such a system usually operates at seventy to 4 that approximately therequired amount of water will always fiow through the pipe 41. I may,however, provide a separate water control valve 59, which is normallyadjusted to the water flow requirements and then remains untouched.

The markedly reduced pressure in the system as described hereinaboveresults in decreased operating costs because of the smaller pressureagainst which the compressor must pump to liquify the refrigerant. Whenthe air temperature is for example 110 the ambient temperature withinthe unit itself in which the compressor and condenser are housed may beas high as or even depending upon the location of the unit. Thisrelatively higher temperature is due to absorption of heat from the.suns rays as well as to the generation of heat because of the workbeing performed by the compressor. When the ambient temperature is highand the humidity is low, the incoming air passing over the compressorand condenser may be as low as 80 so that the cooling action of the airis markedly increased. It is of course known that the higher thetemperature of a gas, the greater the pressure required to condense it.I have found, however, that the operating result of the system of thepresent invention does not appear to be entirely a function of ambienttemperature gradient. High ambient temperature coupled with relativelyhigh humidity is not uncommon, but normally markedly high temperaturesare not accompanied by correspondingly high humidities. In other words,when the humidity is up, the ambient temperature is usually somewhatlower than when the relative humidity is down. While I am unable toexplain the observed facts fully, I have found by actual test that evenduring relatively high humidity periods in the southwest whenevaporative coolers will not efficiently cool a living space, the systemof the present invention still functions with marked increase inefiiciency as constrasted with systems of the prior art.

When an air conditioning system is installed using the improvements ofthe present invention, I have found that the area of the cooling coilmay also be increased thereby making it possible to utilize a lowerhorsepower unit to cool a given space. I have for example successfullyemployed a cooling coil identical with that described hereinabove inwhich the area was one and one-half square feet per compressorhorsepower, and it appears possible to increase the cooling coil to asmuch as two square feet per compressor horsepower so that it will besubstantially the same area as the condenser coil. Increase in the areaof the cooling coil is accompanied by an increase in back pressure butthe back pressure resulting is not greater than the back pressure atwhich systems of the prior art commonly operate. Moreover, it ispossible even with an increased back pressure to still reduce thedischarge pressure of the compressor of the present invention, althoughsuch discharge pressure will be somewhat higher than the dischargepressure maintained when the smaller cooling coil is used.

Regardless of the specific design of the system in which the presentinvention is used and the particular approach made to utilize theresulting efficiencies, there is no water scaling or other deleteriouseffect from the use of the water coolant. Because the water is used onlyintermittently and because only a small amount is employed, the totalburden of hardness in the water is markedly reduced. While inevaporative coolers pads normally must be replaced or cleaned at leastonce or twice a year for suitable performance, the evaporative pads usedin accordance with the present invention have a much longer useful lifeand require little or no attention. There is no added cost of power orconsumption of already existing power in operating the system. Whilevarious known types of water evaporator air cooling units may be used inthe practice of my invention, with or without water recirculation, Ihave found that for many reasons the best and simplest arrangement isthe pad and tap water feed system shown.

I have shown and described one specific embodiment of my invention indetail so that those skilled in the art may understand the manner ofpracticing the same, but the scope of the invention is defined by theclaims.

I claim:

1. In an air conditioning system having a refrigerant compressor andair-cooled refrigerant condenser and means for delivering a stream ofcooling air across the condense, an evaporative pad in the path of saidair stream,

a source of water under normal water system pressure and means fordelivering water from said source to said pad in response to generationof a predetermined pressure in said compressor, whereby to pre-cool saidstream of air by water evaporation.

2. In an air conditioning system having a refrigerant compressor withusual intake and discharge ports, an aircooled refrigerant condenser, aconnection between the compressor discharge and the condenser, a coolingcoil, a connection between one side of the cooling coil and con denser,a connection between the cooling coil and intake side of the compressor,and means for passing a stream of ambient air into contact with thecondenser, an evaporator water to the evaporator pad when the saidrefrigerant pressure reaches about two hundred pounds per square inch.

4. In an air-conditioning system, a refrigerant compressor andair-cooled refrigerant condenser unit including a casing having an airintake opening at one side and an air discharge opening at another side,a blower in the unit positioned to withdraw ambient air through saidintake pad in the path of said air stream, a source of water underopening and exhaust it through the discharge opening to thus provide astream of air moving through the casing, a refrigerant compressor andrefrigerant condenser positioned in said air stream, an evaporatingmember at said intake opening, and means responsive to a predeterminedpressure in the compressor to deliver water to said Water evaporatormember.

5. In an air conditioning system, a refrigerant compressor, an aircooled refrigerant condenser coil unit, means for continuously passingambient air across said condenser coil to cool the same, a cooling coilhaving an outside area over which air to be cooled passes of at leastone and one-half feet square for each horsepower of the compressor, andmeans for adiabatica'lly (reducing the sensible heat of said ambientcooling air passing over said condenser coil when the pressure betweensaid compressor and condenser coil is above two hundred pounds persquare inch, whereby the capacity of a cooling unit to cool a givenspace may be increased.

References Cited in the file of this patent UNITED STATES PATENTS2,231,856 Wetter Feb. 11, 1941 2,655,795 Dyer Oct. 20, 1953 2,995,018Dempsey Aug. 8, 1961

1. IN AN AIR CONDITIONING SYSTEM HAVING A REFRIGERANT COMPRESOR ANDAIR-COOLED REFRIGERANT CONDENSER AND MEANS FOR DELIVERING A STREAM OFCOOLING AIR CROSS THE CONDENSE, AN EVAPORATIVE PAD IN THE PATH OF SAIDAIR STREAM, A SOURCE OF WATER UNDER NORMAL WATER SYSTEM PRESSURE ANDMEANS FOR DELIVERING WATER FROM SAID SOURCE TO SAID PAD IN RESPONSE TOGENERATION OF A PREDETERMINED PRESSURE IN SAID COMPRESSOR, WHEREBY TOPRE-COOL SAID STREAM OF AIR BY WATER EVAPORATION.